Army veteran Melissa Stockwell has one strong, healthy leg. The other is a scarred, 6-inch stump that she has proudly nicknamed "Little Leg."

She throws birthday parties for this shortened limb, always dresses it in her favorite colors - red, white and blue - and has trouble imagining going through life any other way. "I've done more with one leg than I ever could have with two," she often says.

The first female soldier to lose a limb in Iraq, Stockwell, 32, has managed to turn a traumatic above-the-knee amputation into an uplifting experience, one that motivates people of all abilities.

Since the injury, she has shaken hands with presidents, won three consecutive paratriathlon world championships, run marathons, skied down mountains and raced 267 miles across Alaska in the longest wheelchair and hand-cycle race in the world.

Last month she declared on her blog, "I'm going to be an Ironman," and signed up for Ironman Arizona, a punishing 2.4-mile swim and 112-mile bike ride, followed by a 26.2-mile run.

But Stockwell's physical feats only partly explain why a company like Trek, which ended its relationship with disgraced cyclist Lance Armstrong, now touts her as one of their "great athletes," calling her an inspirational role model.

Stockwell also empowers others to become more physically active, healthier and socially connected through her work as a prosthetist, fitting amputees in the United States and Guatemala with new limbs.

Training group

In 2011, she co-founded Dare2Tri, a triathlon training group for people with disabilities, where she works as a coach and mentor, often swimming, biking or running alongside her athletes.

Stockwell is also an instrumental part of Blade Runners, a running group for amputees, and is active in organizations ranging from the Wounded Warrior Project to the Challenged Athletes Foundation.

"Melissa understands what her role is on the planet," said her coach, Stacee Seay, national manager for TrainingBible coaching and the head coach for Dare2Tri. "Her injury does not define her, but it certainly, certainly makes her who she is today."

An estimated 25 million Americans have a mobility impairment - including 6,144 U.S. troops who have lost limbs in Iraq and Afghanistan.

Physically inactive

"This group remains one of the most physically inactive and obese groups in our society," Rimmer said. Some studies suggest that "disabled people on average spend 18 hours a day sitting down or lying down, and 1 in 6 are completely inactive 24 hours a day," he said.

Exercise, in addition to building strength and stamina, can also have a powerful psychological effect on those with disabilities. For Stockwell, moving makes her feel whole again.

Stockwell, the youngest of three girls, has always been passionate about sports, the American flag and her country. "She'd get goose bumps just hearing the national anthem," said her mother, Marlene Hoffman.

A competitive gymnast, diver and pole vaulter during high school in Minnesota, she joined the ROTC while studying communication at the University of Colorado.

Stockwell had been in Iraq just three weeks when she lost part of her left leg to a roadside bomb April 13, 2004 - a day she now celebrates as the arrival of Little Leg.

A platoon leader and first lieutenant, her convoy had been traveling under a bridge in Baghdad in an unarmored Humvee when she heard a deafening explosion. Her leg was stinging; when she looked down, she saw a pool of blood where a leg should have been.

"I remember knowing it would be OK," she said. "I know that sounds weird, but I knew it would be."

It took Stockwell three months to relearn how to walk using her first prosthetic. After a year of rehabilitation and recovery from more than a dozen surgeries and complications from infections, she skied on one leg with the Vail Veterans and took up swimming, a sport she could manage without the prosthetic leg.